Damping gyroscopic compass



A Nov. 22, 1927.

H. l..l 'rANNr-:R

DAIIPING GYROSCOPIG COMPASS Filed July 29. 1921.

Patented Nov. 2z, 1921. i

UNITED STATES PATENT OFFICE.

HARRY L. TANNER, OF BROOKLYN, 'NEW YORK,` ASSIGNOR TO FORD i INSTRUMENT COMPANY, INC., OF NEW YORK', N. Y., A CORI'PORATION 0F NEW YORK.

DAMPING GYROSCOPIC COMPASS. i'

Applieauqn med nuyea,

This invention relates to damping gyroscorpic Compasses and more particularly t the damping of the oscillations about the meridian of the ljyroscopic'elements of coml passes of the type shown in my co-pending application Serial #469,201 filed May 13, 1921.

The comp-ass shown in that application comprises a gyroscopic element consisting of a. mass which is arranged to spin about an axis having a substantially constant inclination to the surface of" the earth and normally bearing' a fixed relation to the plane of the meridian, and a case which surrounds and serves as a support for the mass and may turn in the plane of the latter about the inclined axis independently of the rotary movement of the mass within the case. 'I he case is mounted within an inner suppo-rtmg 0 member upon an vaxis lying in the plane of the case and\in the plane of the meridian when the caseoccupies its normal position. The inner supporting member is mounted upon a normal east-west'axis within another r sup-porting' member which in turn is mounted lupon an lnner frame which may carry the compass card and 1s 1n\tu rn lmovably mounted upon an outer Jrame which as mounted to turn 'with the craft on which the compass is carried. The inner frame is adapted to be moved by a driving element, such las a servo-motor` controlled by contact mechanism consisting of two relatively movable parts one of which is connected t0 the case, or to ya. part of the'instrument adapted to move with the case, and the Other the instrument, such as one of the support` of which is connected to some other part of ing members, whichbears a iixedrelation to the case when the latter occupies 'its normal position, but which is displaced with respect t-o the case when the latter is turned about the rotatable mass by relative movement between the inner and outer frames due to changes in course of the craft or while the gyroscopic element is seeking` the meridian, which it is caused to do by the effect of gravity upon t-he element which is made pendulous about itssupportinp; axes.

Inl a. compass such as described above, it

1921. Serial N0. 488,349.

lustration, two arrangements which may be employed forthis purpose have been shown ii` my copendingl application in connection with the compass forming the subject matter thereof. Onearrangement consists of na mass-which is attached to the case in the 'voirs mounted on the element in the north south plane and connected by a restricted passage. v

As explainedin detail in my co-pending application, the use of a dampin arrangement such as the first one referre requires that a correction be applied for latltude in order that indications may be obtained free from error. It also requires the use, of extra parts. The employment of a liquid level arrangement, such as shown in my copending application, while eliminating the necessity for applyinga latitude correction, also requires the addition of eXtra arts and a careful regulation of the How of llquid between the reservoirs. p

This invention has for .an object the damping of the oscillations of a gyroscopic compass, particularly of the type shown in my co-pending appl1cation, by the abtion of to above,

the torque which causes such oscillations and in such a manner that indications may be ob- `tained which will be practically free from error, so that the necessity for applying corrections will be elimlnated, and `auxiliary devices maybe dispensed with, whereby the construction of the instrument is simplified and lts cost 1s reduced. l

In accordance wlth the invention, a gy'roscopic element having its plane of rotation at a substantial angle to the horizontall is moved by the effect of themeridian seeking torque about an axis which bears such a relation to the spinning axis of the rotor that movement of the case of the elementabout the spinning axis will have a. com onent which will cause a change in the incllnat-ion of the element in a direction tending to reclination which it possesses in accordance with the invention of my copending application an east-west inclination. 1t results from these two inclinationsof the element that its high and vlow points will be displaced sidewise from the positions which they occupy when the elementis arranged as shown in that application. Since the gyroscopicelement is pendulous, a torque will be applied about its east-west supporting axis during meridian seeking oscillations to cause precession about the other supporting axis. When the high and low points of the element are displaced in accordance with the present invention, the movement of the element caused by such procession in combination with the movement imparted to the case of the element by the servo-motor will have a component which will tilt the element in la direction to reduce the deviationsv from its normal inclination as it oscillates about the meridian, thereby damping the oscillations and rendering the compass suitable for use upon a moving craft.

The particular nature of the invention will appear more clearly from a description thereof taken in connection with the accompanying drawings in which- Figure 1 is a plan view, with parts omitted for the sake of clearness, of a simple form of compass adapted to be dampedfin accordance with this invention, the parts being shown in the relation which they occupy when the craft upon which the compass is mounted is heading north, l

Figure 2 Iis asimplitied elevation, partly in section of the instrument of Figure 1,

` viewedv from the west,

Figure 3'is a similar view of the instrument viewed from the south, .Y

Figure 4: is a diagrammatic representation in plan of the gyroscopic element of an undamped instrument,

Figure 5 is a similar representation of the gyroscopic element arranged in accordance with this invention,

Figure 6 is a diagrammatic representation in sectional elevation of the gyroscopic ele-v ment with a vector diagram superimposed thereon, v

Figure 7 is a similar representation of the gyroscopic element of.Figure 4 viewed at right angles to Figure 6 and Figure 8 is a corresponding representation of the gyroscopic element of Figure 5.

Referring particularly to Figures 1, 2 and medica provided with trunnions 6 6 mounted in4 bearings in a second ring 7 which, on account of its function will he hereinafter referred to as the stabilized ring of the instrument. The gyroscopic element and its supporting ring 5 are mountediii an inclined position as shown most clearly in the elevational view Figure 2 by displacing the axis 6-6 from the center of gravity of the v element so that the element is pendulous and maintains a certain inclination iz to the surface of the earth when the rotor is not spinning. y

As explained in detail in my copending application referred to above, this angle will be constant for all positions of the coinpass, but when the rotor is spinning the inclination of the element will differ from its inclination when the rotor is at rest by an angle which depends upon the latitude and another angle which depends upon the east west component of the speed of the craft upon which the compass is carried.

rllhe stabilized ring 7 is rovided with trunnions 8, 8 disposed at right angles to the trunnion axis 6 6 and in the plane of the trunnion axis 4-4- The trunnions 8, y8

are mounted in bearings in an inner frame or shell 9 adapted to be power driven and bearing a scale graduated in units of an lar measure. This frame is rotataly mounted within an outer frame or shell 10 as by means of balls 11. The frame 10 bears the lubbers line of the compass and is provided with trunnions 12, 12 adapted to fit in bearings in the gimbal rings of the binnacle, which have been omitted from the drawing for the sake of simplicity.

The element 9 is -adapted to be driven by a servo-motor 13 in any suitable manner, as by means of apinion meshing with a gear attached tov the element. The circuit of the servo-motor is controlled by a device consisting of a contact 14 mounted on the case and adapted to engage one or the other of two contacts 15 mounted upon the ring 5 to cause the servo-motor to rotate in one direction or the other. For simplicity the circuit connections between the device and the motor have been omitted.

The stabilized ring 7 ypair of depending brackets 16 disposed in the north-south plane and carrying at their lower ends a ring 17, Within which is mountved a stabilizing gyroscope 18 having its other end is attached to an adjusting device mounted on the stabilized ring 7, whereby the planes of the rings. may be adjusted relatively to each other for the purpose of applying the necessary corrections for course and speed of the craft upon which the couipass is mounted, as explained in detail in my copcnding application ret'erred to above. In the form of instrument shown iii that application the only permanent inclination a of the -gyroscopic element. consisting ot' the rotor- 1 and case 3, is about the east West axis 6 6, Which is horizontal. so that the element occupies the position shown in Figure 4 with its highest point A in the rertical plane of the axis 4--4L'rr In accordance with this invention an axisy of the gyroscopic element lying in the plane of the element and perpendicular to the axis 4 4 is also given a permanent inclination Vby balancing' the element so that one side, the east' side as shown herein, is higher than the other side as shown most clearly in Figure 3. The highest. point of the clement will thus be displaced to one side ot' the vertical lane of the axis 4 4, as shown at A .in *igure 5. The axis 2 2 instead of lying in the plane of the meridian in the torni ot instrument shown in my copending appli cation will thus be inclined to 'this plane. The plane of the inner ring 5 is preferably given a corresponding inclination as by elevating its east trunnion 6 as compared -With its west trunnion 6, or, in ease it is desired to keep the axis6 6 horizontal, the trunnions 6, 6 may beshifted to points differing .from ninety degrees from the axis 4-4. In either case the supporting axis 4- 4 of the gyroscopic element will iii-.ike an angle` substantially diiferent from ninety degrecs With a horizontal axis lying in its plane of rotation. The contact 14 upon the case 3 and the contacts' 15, 15 upon the ring 5 are so arranged that they occupy their neutral position when the gyroscopic element is upon the meridian with its plane coinciding with the plane of ring It the element does not occupy such a position the contact 14 will be in engagement with one or the other of the contacts 15 to cause' the servo-motor 13 to be energized to turn the frame 9, the ring` 7, the ring 5, and the case 3 attached theretok by the trunnions 4, 4, in .a direction to turn the case about the axis of the rotor until it. assumes such a position that the contact 14 occupies its normal relation to contacts 15, 15 with thev entire element balanced in its tilted. position about the axis 4 4. In other Words. the action of the servo-motor will be such as to maiiiv'tain the vrotor and case in their inclined position with respect to the axis 4 4.

axis 6 6 of the main gyroscope, as b tilting the ring 17 withinwhich the stabilizing gyroscopey is mounted upon trunnions 2.1, 2l.y gyroscope is for the purpose of preventing errors which would otherwise be introduced it' the plane of the Vmain gyroscope were tilted by au'auglc without a correspond-I ing tilt of the plane ot' the stabilizing gyroscope. v

vIii considering the meridian seeking action ot the instrument described above itwill` be assumed that the rotor l of the main gyroscope is turning clockwise as indicated by the arrows appearing at the Ventilating apertures in Figure 1. It will also be assumed that the contact 14 occupies its neutral position with respect to t-he tWo'cooperating contacts 15 so that the servo-motor '12S is not energized. It will be most convenieiit to regard the element 9 as having been turned iii a clockwise'direction through 90 from the position shown in igure 1 so that the axes 4 4 and 8 8 lie in an east-West direction'with the high side of the gyrolscopic element toward the east.

Iii accordance with the principle of the gyroscope the plane of rotation of the rotor 1 wfll remain l'ixed in space. As the earth tui-iis from under the rotor dueto its rotation, tlie high side of the rotor will rise relatively to the surface of the earth carrying tlievcase with it. This will cause the pendiiloiis mass ot the rotor and case to be shifted from its position .ofequilibriuin 'lhis displacement will produce a torque about the Supporting axis 6 6 which Will cause the rotor and case to precess about the inclined axis 4- 4, .thus displacing their plane with respect to the plane ot' the inclined ring 5. This precessionof the rotor and. case will shift the contact 14 rfrom its neutral position with respect to the contacts 15 into Vengagement with one of these conltacts, thereby energizing the servo-motor 13 so that it rotates iii a` direction to turn the element 9 counterclockwise to carry the axes 4 4 and 8 8 toward the meridian. As the movable parts of the instrument Aturn toward the meridian-,the inclination. of the gyroscopic element will gradually increase as the earth continues to turn away from under it, thus increasing the torque about the axis 6 6. The rotor and case will therefore process about the axis 4 4 at an increasing rate, and the contacts 14 and 15 wll keepthe servo-motor energized and the element 9 in motion. The axes 4 4 vand and toward the west. This westerly movementwill continue until the contact 14 again assumes its neutral position with re speci: to the contacts 15 to cle-energize the seri-'o-iiiotor'lf. This will not occur until procession about the a-Xis 4 -4 has ceased due This inclination of the stabilizing y8 8 will thus be carried past the meridian )to the absence of torque about the axis 6 6. Allhis last named condition will obtain when the parts of the instrument have turned so tar toward the west that the gyroscopic eleyment lies at its normal inclination with respect to the surface or" the earth, due to the itact that in the new position ofthe eleent the 'earth is turning toward the plane of the rotor instead ot away from it as at Lthe beginning of the cycle of operations de-V scribed above. j

After the gyroscopic element has reached the western limit of its oscillation the movement of the earth toward it will result in a depression of its high side relatively to the surface of the earth due to the ixidity of the plane of rotation of the rotor. rlhis depression of the high side of the element will result in shifting its center' of gravity to produce about the horizontal axis 6 6 a torque which will be in the opposite direction to that produced when the element is` This at its eastern limit of oscillation. torque will cause precessionof the rotor and case about the axis 4- 4 in such a. direction as to shift the contact 14 from its neutral position with respect to the contacts 15 into engagement with the other contact-15 oppo site to that which was engaged by the contact 14 during the east to west`movement of the gyroscopic element. 'llhe servo-motor 13 will thusibe ermrgized to rotate in a direction to turn the power drivenA element 9 ,clockwise thereby swinging the axes 4 4 and 8 8 acrossv the meridian toward the cast. As the parts move from the west toward the meridian the inclination of the gyroscopic element -with respect to the surface of the earth will continue to decrease since the earth is turning toward the element.

rllhe torque about the axis 6 6 due to they shifting of the center of gravity of the ele- 'ment will thus be increased as will also the .@precession of the rotor and case about the axis 4 4. 'If the compass be undamped its gyroscopic element will cross the meridian from west to east with theraxis 4 4 de! pressed asV far below its normal inclination 'as it was raised above this inclination when it crossed the meridian from east to west.

The damping action of the instrument will appear mostv clearly `with the aid of the diagrams constituting Figs. 4 to 8 inclusive, and in connection with this explanation the action of an undamped gyroscopic element, such as shown in Fig. 4, will be Aconsidered first. During the oscillations of such an element there will be a relative movement ot thc case with respect to the rotor about the axis 2 2 of the latter independently ot' the rotation of the rotor within the case. In other words, duing meridian seeking oscillations the case 3 will turn in the plane of the rotor about the axis 2 2 common to it and the roordinarily obtain in maaien thel movement of the case due to its preces-` sion about the axis 4 4 caused by the torque about the axis 6 6. "lh resultant of these At the same time that the case 4two vectors is a vectoor-a d lying in the plane determined by the axes 2 -2 and 4-4, and in a vertical pla-ne through the axis 6 6.. ln the case of an undamped element, such as shown in Figure 4, the plane of the axes 2 2 and 4 4 is vertical so that the vector a d is vertical, showing that the resultant movement of thegyroscopic element is about a vertical axis. 'This vector rep.-

resents the entire movement of the element, except that due to the" rotation of the earth, which for the 'purpose of the present explanation of the damping action may be disregarded.

Considering the gyroscopic element shown in Figure 5 in which the plane of the element has been tilted through an angle which for fclearness of disclosure is .somewhat exaggerated over that which would n practice, it will be seen that the axis 2 2 a out which the case is moved by the servo-motor lies in a plane which is inclined to the vertical. The movement of the case about the axis 2 2 and precession of it and the rotor about the axis 4 4 may be represented by the vector diagram of Figure 6, but-on account 'of the` tilt of the element the plane of the axes 2 2 and-4 4 in which the resultant vector a d lies is inclined to the vertical. This is shown most clearly in Figure 8 which rep.

resent-s the gyroscopic element in section in a vertical plane through the axis 6 6. The resultant vector a d" lies in this plane and in the plane 'of the axes 2 2 and 4 4, and as in the case of the vector a cl of Figure 6 it represents the entire movement. of the gyroscopic element, except that due to the movement ofthe earth, which may be disregarded.

The vector a if may be resolved into vertical and horizontal components lying in the vertical plane through the axis 6 6. The' component a e represents the movement of the element about a vertical axis while the component a f represents a movement of the element about a horizontal axis.

It has been explained that as the gyroscopic element oscillates .about'the meridian its inclination will vary from the normal in clination a, being greater than this angle during movement from east to west and less mass of the' element' which `produces the! 'damped forms of gyroscopic element instrument is simplified, its cost is reduce torque which causes the element to seek the meridian. 'The 'effect of the movement or the element represented by the component a f vvill be to lessen its deviation from the normal inclination as it moves back and forth across the meridian. In other Words, this component represents a movement about a horizontal axis in a. direction tending to lower the center of gravity of the' element and bring it back to its normal positionwith respect to such an axis, thereby damping the oscillations about the meridian.

The diierence between the undampedv and -ma also be seen by comparing Figure 7 witli Figure 8. In-the former figure the resultant a d lies in the vertical planes of the axis 6 6 on the one hand and the axes 2 2 and on the other hand, and it has no horizontal component, such as does the resultant a d of Figure 8. This means that there is no component movement about a .horizontal axis, that is'about the axis 6 6 in the undamped form of'element, and therefore no damping effect when the element is arrange as in Figure 4 with its highest point A. in the plane of .the axis 4 4. l

' It' such an undamped gyroscopiqelement be not affected by any otherfexternal forces, the friction between its moving arts would cause its oscillations to gradual y diminish in amplitude until it reached a' settling point with its axis 4 4 lying in the 'plane of the meridian and at its normal inclination to the surface ot the earth. The time re uired for such settling of the element Wou d be too long even if the co1npass^were used on land, but if it were used on shipboard, as

`would be the usual case, the impulses due to the rolling of the ship and other causes would Icause the instrument to oscillate indefinitely so that it might never settle upon the meridian.

"When the element is arranged in accordance with this, invention with it-s plane inclined at an angle the inclination of the element about lthe axis 6 6, or in other Words, the inclination of its north-south axis 4 4, rapidly approaches the normal value a during the oscillations about the meridian, and the`element settles` with its axis 4 4 lying in the plane of -the meridian and at its normal inclination with respect to the surface of the earth. This damping of the element is obtained without the use of rny auxiliary devices so that the structure of the and all of the other disadvantages attending the use of such devices are eliminated. As explained in detail in my copending application referred to above, an undamped forni of gyroscopic element, arranged like the one shown in Figure 4 herein, automatically takes care of changes in latitude of the compass ithout the necessity for applying corrections, but when a damping arl rangement consisting of amass suspended from the case of the element, as shown in that application, 1s employed a latitude correction is required, which may be applied by shifting the stabilized ring 7 by means of the member v19 and adjusting device 20; When the damping arrangement of the present invention is employed there is no necessity for applying a latitude correction because the gyroscopic element is .subject to.

practically no deviation due to changes in the earth,` the same as is an undamped form of compass. In other Words the tilt imparted to the element, which will beslight, will not materially affect the action ofthe element in automatically taking care of changes in latitude.

While an application of the invention to the particular form of gyroscopic compass shown in my copeiiding application Serial No.L` 469,201 has been shovvn and described herein, it will be understood that it may be d applied to gyroscopic Compasses of other forms and that various changes in the details of construction may be made without departing from the principle of the invention .as defined in the appended claims.

1. In a meridian seeking gyroscopic coinpass, a gyroscopic element, andA means for supporting the element upon two mutually perpendicular axes, both of which are inclined to the surface of the earth.

2. In a meridian seeking gyroscopic compass, a gyroscopic element and means for supporting the element with its spinning axis inclined to the plane of the meridian and also at a considerable angle to the surface .of the earth, When'the element occupies its normal direction indicating position.

3. In a meridian seeking gyroscopiccompass, a gyroscopic element and means forV supporting the element with its spinning axis inclined to the plane 'of the meridian and also ata considerable angle to the surface of the earth, when the element occupies its normal direction indicating position, the upper end of the spinning axis of the element lying in the south-West quadrant of the plane of the meridian and an east-west vertical plane.

4. In a gyroscopic apparatus, the combination of a rotatable mass, a support for the mass, a member within which t e support is mounted upon an axis inclined with respect d to the surface of tlreearth and lying at right (position or the compass upon the surface of angles to tbe spinning axis of the mass ana second member Within which the first named member is mounted upon an axis inciined with respect to the surface of the earth and iying at right angles to the first named axis and to the spinning axis of the mass.

A 5, iin/a gyroscopic compass, a gjyroseopic element comprising a rotor and. a case, means for mountin the rotor and ease u on mutuaiiy perpendicular supporting axes so that they may turn about a common inclined axis independently of each other, means or causing' continuous rotation of the rotor about lious with respect to the supportin `whereby it is caused to seek the meri 1an byA Lemme the common axis, said eiement being penuaxes the action of gravity thereon, and means for turning the case about the common axis during such meridian seeking movements, both of said supporting axes being inclined to the surface of the earth `whereby oscilations oit the eiement are damped by the joint laction of the pendulous mounting or' the element and the turning means.

in testimony whereof i ax my signature.

HARRY L. TANNER. 

